1. Field of the Invention
This invention relates to improvements in a zoom lens, and specifically to improvements in the zoom lens disclosed in Japanese Laid-open Patent application No. 135750/1977 (U.S. Pat. No. 4,155,629).
2. Description of the Prior Art
In a zoom lens comprising a forward group which is a divergent lens group and a rearward group which is a convergent lens group as a zoom lens covering a wide angle of view, correction of various aberrations and correction of the fluctuations of the various aberrations caused by zooming are of course important, but making the entire lens system compact for simplicity of the mechanism has been a matter of concern. According to the prior art, it is disclosed in Japanese Laid-open Patent application No. 135658/1978 that the total length of the lens system is minimum when the focal length of the entire system becomes equal to the absolute value of th focal length of the divergent lens group and that the total length increases when the focal length of the entire system is longer or shorter than said absolute value. Therefore, in Japanese Laid-open Patent application No. 132360/1978, it is described as the condition for compactness of a lens system that the absolute value of the focal length of the divergent lens group is set within the range of the focal length over which the focal length of the entire system is varied by zooming, or to a value very approximate to the focal length of the entire system at the telephoto end. However, such lens system is generally designed as a lens system which covers a relatively short focal length range and the focal length of the entire system at the telephoto end is not so long. Therefore, the power of the divergent lens group therefore has unavoidably become considerably strong. To eliminate the burden in aberration correction which results therefrom, such lens system has adopted means for thickening each lens group and thus, it may not safely be said that the effect of making the lens system compact has been achieved so well.